Man what a find, this is a vegan's dream.
I was here with a couple of Thai friends, and between us we got several dishes totalling just 170 baht, leaving all three of us stuffed. The food was just very local, no thrills Thai food.
If you're a vegan as I am, you can probably appreciate the frustrations of seeing a delightful, local Thai lunch buffet, but walking straight passed because you can't be sure what contains meat and what doesn't. It's that same type of thing, with the same prices (I didn't see any dish that cost more than 25 baht), but everything here is vegetarian (and I think vegan, although I can't be sure).
English is very limited, and although I was here with Thai friends, when they were sat down or at another vendor, I found that any Thai working here who did speak English was happy to translate. This included the manager of the place, who was a fairly young girl who was clearly passionate about this place, asking me how I'd heard about it, wanting to make it a success.
All I'll say is that if you're vegetarian / vegan, and want local food at local prices without the worry it contains meat or fish sauce or anything else, then this place is your dream. I can assure you I'll be going back here again.
I especially recommend it on weekends as its near, almost in the Chattuchak Weekend Market.